Woven filter cloth



March 24, 1970 R. A. CRAWFORD WOVEN'FILTER CLOTH Filed Nov. 29, 1967 v JZw/mmZQ Cmwfo 7%.

- JW MM United States Patent M ABSTRACT OF THE DISCLOSURE Dutch like woven filter cloth having warps and wefts in which the wefts are driven up close to provide mesh openings of triangular configurations characterized by the warps being of greater yield strength than the wefts, the wefts being of greater cross sectional area than the warps, and the crimps in the wefts being substantially greater than the crimps in the warps.

The concept of the present invention lies in the utilization of high strength warps as compared to the strengths of the warps of known Plain Dutch and Twill Dutch weaves of the prior art as well as to the strength of the wefts of the prior art weaves and the weaves of this invention which enables the utilization of warps of less cross sectional area than that of the wefts. As a consequence for a given area of filter cloth of a given micronic rating as compared to known filter cloths, substantial savings are effected due to materially reduced costs of weaving and the utilization of less expensive weft material. Further, the beating up of the larger diameter wefts and by reason of their large cross sectional area, results in a physically stable and strong filter cloth in the weft direction. and the use of higher strength warps results in a strong filter cloth in the warp direction.

According to the present invention, the cross sectional area of the warp provides a tight or greater warp mesh for a comparable Weft size than prior known filter cloth weaves and together with the utilization of wefts of large diameter than before used, the warp mesh and diameter may be varied to provide the desired micronic rating for the filter cloth. The high strength warp wire permits larger annealed weft wire to be formed against it, and the high strength warps also provides for a tighter warp mesh in the filter cloth combined with the larger annealed wefts.

The foregoing may be perhaps better understood by comparison of typical examples of filter cloths of known Dutch weaves and the filter cloths of this invention.

One known Twill Dutch weave typically may comprise an 80 x 700 mesh with the warps being .004" in diameter and of soft annealed stainless steel, and the wefts being .003 of conventional weft material having an absolute micronic rating of 40. By contrast a typical example of a Twill Dutch-like filter cloth of this invention having an absolute micronic rating of 40 comprises a 100 X 425 mesh in which warps of .0025" are of hard drawn 302 stainless steel, and the wefts of .0033 are of conventional Weft material. It will be noted that the mesh of this invention has a larger weft diameter than the 80 X 700 mesh and 20 more warps per inch. Also the warp yield strength of the given example of filter cloth of this invention is about eight times as great as that of the above example of prior art filter cloth. The wefts of both the example of the prior art cloth and the typical given example of this invention have the same unit strength with the prior art filter cloth numbering 700 wefts of .003" diameter, against 425 wefts of .0033" diameter of the example of this invention. In the above comparison the individual wefts of the given example of this invention have 20% more cross-sectional area than the individual 3,502,116 Patented Mar. 24, 1970 wefts of the prior art example. Further, the individual warps of. the above example of the invention due to their higher warp mesh and higher unit strength produce a mesh whose strength in the warp direction is about 4 times stronger than the typical prior art example.

By comparing the foregoing examples, it will be observed that the filter cloths of the invention are of considerable economic advantage in the utilization of less costly wefts. In addition the weaving cost is substantially less. The greater diameter of the wefts with respect to the war-ps also provides for increasing the mechanical strength of the woven filter cloth in the weft direction and which, together with the high strength warps provides a mechanically strong filter cloth. Further, since the wefts are beat up on the high strength warps considerable crimp is imparted to the wefts interlocking the wefts and warps providing a stable filter and avoiding any sleaziness which is present in many known Plain and Twill Dutch weaves.

The wire cloth filter of the present invention as will be understood from the foregoing does not respond to the conventional and accepted weave definitions used in the art today. Accordingly, in this specification and in the appended claims, the phrase Dutch-like type woven filter cloth is to be construed as meaning woven cloth in which the mesh openings are of triangular or wedged shaped configuration. Also, in the filter cloth of the present invention, the warps may be formed of any suitable high strength material of which hard cold drawn type 302 stainless steel is an example. The wefts may be formed of any conventional materials employed as wefts in the Weaving art today. Again, for purposes of this specification and the appended claims, the wefts shall be referred to as being composed of ductile materials which includes any of the common and known materials for such purpose, such for example, as copper, brass, bronze, Monel, aluminum, stainless steel, titanium, plain steel and nickel and in which such weft materials are characterized by having a 10 percent minimum elongation.

The above and other objects and advantages of the invention will appear from the following detailed description of certain preferred embodiments of the invention shown in the accompanying drawings in which:

FIGURE 1 is a perspective view of a portion of a filter cloth of the invention in which the wefts are in one over, one under, and one over etc. relation with respect to the warps;

FIGURE 2 is a perspective view of a portion of a filter cloth in accordance with another embodiment of the invention in which the wefts are in two over, two under, and two over etc. relation with respect to the warps and in changing the pairs of warps with each successive weft by displacing one wire to the right or left in the manner of a twill weave;

FIGURE 3 is a perspective view of a portion of a filter cloth according to another embodiment of the invention in which the warps comprise a plurality of filaments in lengthwise touching engagement and in which the wefts are in one over, one under, and one over etc. relation with respect to the warps; and

FIGURE 4 is a perspective view of a portion of a filter cloth in accordance with still another embodiment of the invention in which the warps comprise a plurality of filaments in lengthwise touching engagement and in which the wefts are in two over, two under, and two over etc. relation with respect to the warps and in changing the pairs of warps with each successive weft by displacing one wire to the right or left in the manner of a twill weave.

The filter cloth 5 shown in FIGURE 1 comprises a plurality of warps 6 and a plurality of wefts 7. The warps 6 are of smaller diameter than the wefts 7 and the warps 3 6 are fabricated of materials having a yield strength in excess of the yield strength'of the wefts 7. A typical filter cloth of FIGURE 1 may be way of example a 100 x 450 mesh in which the warps 6 are of a diameter of .0025" composed of type 302 stainless steel having a yield strength of 400,000 p.s.i. The wefts 7 may be of a diameter of .0027" composed of type 304 stainless steel having a yield strength of 50,000 p.s.i. In the specific example of filter cloth it is characterized by an absolute micronic rating of 25 microns.

The filter cloth shown at 8 in FIGURE 2 comprises a plurality of warps and a plurality of wefts 9. The warps 10 are of smaller diameter than the wefts 9 and the warps 10 are fabricated of materials having a yield strength in excess of the yield strength of the wefts 9. The warps 10 are formed of material having a yield strength of 250,000 p.s.i. or greater and the wefts 9 are preferably of material having a yield strength of the order of 50,000 p.s.i.

The filter cloth 8 may be of the construction of the example of the invention above given for comparative purposes with an example of a twilled Dutch filter cloth of the prior art.

Another example of filter cloth 8 may be a 70 x 380 mesh in which the warps 10 are formed of .004 inch hard drawn type 302 stainless steel. The wefts 9 may be .0055 inch in diameter and formed from annealed type 304 stainless steel. The warp wires 10 in the example last noted are characterized by an average yield strength of 334,000 p.s.i. whereas the yield strength of each of the wefts 9 is of the order of 50,000 p.s.i. The filter cloth 8 constructed within the last noted foregoing parameters has an absolute micronic rating of 42 microns. Another example of the filter cloth 8 of FIGURE 2 may comprise a 60 x 230 mesh in which the warp wires 10 are .0055 nch in diameter and formed from hard drawn type 304 stainless steel which is characterized by an average tensile strength of 260,000 p.s.i. The weft 9 in this example may be .0075 inch in diameter and composed of annealed type 304 stainless steel which is characterized by a tensile strength of 115,000 p.s.i. In this last described filter cloth the absolute micronic rating is 54 microns.

As a further example the filter cloth 8 of FIGURE 2 may comprise a 60 x 300 mesh having warps of Monel of .0055" in diameter and of a yield strength of 160,000 p.s.i. and wefts of Monel of .007" in diameter and a yield strength of 35,000 p.s.i. to provide an absolute micronic rating of 49.

In the woven filter cloth 14 of FIGURE 3 the warps 15 each include a pair of lengthwise extending touching filaments 16, and in which the wefts 17 pass over one, under one and over one etc. of the warps 15.

In the species of the invention shown in FIGURE 4, the woven filter cloth 18 again comprises warps 19 defined by lengthwise extending and touching pairs of fila ments 20, and in which the wefts pass over two, under two, and over two etc. of the warps 19, with wefts 21 in alternating relation as shown in the drawing to provide a twilled Dutch-like weave.

The warps and wefts of the filter cloths 14 and 18 may be of materials and parameters as before discussed.

The several filter cloths shown in FIGURES 1 through 4 are constructed to come within the aforegoing defined Dutchlike type woven filter cloth and are characterized by the warps being formed of high strength material compared to the strength of the wefts, and in which the several wefts of the several filter cloths are of greater crosssectional area than the warps and formed of materials according to the aforedefined expression ductile materials.

It will be understood that the warps and wefts may be of other than circular cross-sectional configuration it being important only that the ratio of the cross-sectional area of the wefts to cross-sectional of the warps be greater than that of the prior art, which is about'.4 to .7.

It will be understood that various modifications and rearrangements may be made in the woven filter cloths of the present invention without departing from the spirit and scope of the invention.

The invention claimed is:

1. Dutch-like type woven filter cloth comprising warps and wefts in which the wefts are driven up close resulting in mesh openings of triangular configuration, said warps being of greater yield strength than said wefts, said wefts being of greater cross sectional area than said warps, and in which the crimps in said wefts are substantially greater than the crimps in said warps.

2. The woven filter cloth of claim 1 in which said warps have a yield strength of at least 50% greater than the yield strength of said wefts.

3. The woven filter cloth of claim 1 in which the several warps are of the same diameter and are disposed in non-engaging side-by-side relation.

4. The woven filter cloth of claim 1 in which the warps each comprise more than arsingle filament in sideby-side touching relation.

5. The woven filter cloth of claim 1 in which said warps are hard drawn stainless steel having a yield strength of at least 250,000 p.s.i. and in which the wefts are of ductile material.

6. Dutch-like type woven filter cloth comprising warps and wefts in which the wefts are driven up close resulting in mesh openings of triangular configuration, said warps being in as drawn condition, and said wefts being in annealed condition, said wefts being of greater cross sectional area than said warps, and in which the crimps in said wefts are substantially greater than the crimps in said warps.

7. The woven filter cloth of claim 6 in which the warps comprise more than a single filament in side-by-side touching relation.

References Cited UNITED STATES PATENTS 3,006,384 10/1961 Brown et al. 139-4255 3,100,729 8/1963 Goller 2458 X 3,139,119 6/1964 Buchanan 139--425.5 3,167,281 1/1965 Hill 2458 3,327,866 6/1967 Pall et al. 139425 X 3,329,378 7/1967 Stanton 2458 1,078,380 11/1913 Reynolds 2458 1,889,463 11/1932 Cederberg.

2,462,604 2/ 1949 Boucher 139-425 X 2,755,047 7/1956 Henke -1 2458 2,775,550 12/1956 Harlow 2l0499 X 2,992,681 7/ 1961 Hornbostel et al.

3,231,091 1/1966 Kingsbury et al. 2l0499 OTHER REFERENCES The Cambridge Wire Cloth Company, Cambridge, Md., pp. 1 and 15, received in the US. Patent Ofiice Feb. 19, 1932.

Monel Wire Screen and Filter Cloth, Bulletin H-3, pp. 6 and 7, by the International Nickel Co., Inc., 1940.

JAMES KEE CHI, Primary Examiner US. Cl. X.R. 

